<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<script>
    var num = 10;
    var Num = 20;
    var num = 10, num2 = 20;
    var aa = '你好吗';
    var bb = "你好吗";

</script>
</body>
</html>